Commit 4e2a44c1 authored by Jiri Slaby's avatar Jiri Slaby Committed by Greg Kroah-Hartman
Browse files

tty: add kfifo to tty_port 



Define a kfifo inside struct tty_port. We use DECLARE_KFIFO_PTR and let
the preexisting tty_port::xmit_buf be also the buffer for the kfifo.
And handle the initialization/decomissioning along with xmit_buf, i.e.
in tty_port_alloc_xmit_buf() and tty_port_free_xmit_buf(), respectively.

This allows for kfifo use in drivers which opt-in, while others still
may use the old xmit_buf. mxser will be the first user in the next
few patches.

Signed-off-by: default avatarJiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20220124071430.14907-4-jslaby@suse.cz


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 702d10a0

drivers/tty/tty_port.c

+5 −1
Original line number Diff line number Diff line
@@ -225,8 +225,11 @@ int tty_port_alloc_xmit_buf(struct tty_port *port) 
{

	/* We may sleep in get_zeroed_page() */

	mutex_lock(&port->buf_mutex);

	if (port->xmit_buf == NULL)

	if (port->xmit_buf == NULL) {

		port->xmit_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);

		if (port->xmit_buf)

			kfifo_init(&port->xmit_fifo, port->xmit_buf, PAGE_SIZE);

	}

	mutex_unlock(&port->buf_mutex);

	if (port->xmit_buf == NULL)

		return -ENOMEM;
@@ -240,6 +243,7 @@ void tty_port_free_xmit_buf(struct tty_port *port) 
	if (port->xmit_buf != NULL) {

		free_page((unsigned long)port->xmit_buf);

		port->xmit_buf = NULL;

		INIT_KFIFO(port->xmit_fifo);

	}

	mutex_unlock(&port->buf_mutex);

}

include/linux/tty_port.h

+3 −0
Original line number Diff line number Diff line
@@ -2,6 +2,7 @@ 
#ifndef _LINUX_TTY_PORT_H

#define _LINUX_TTY_PORT_H



#include <linux/kfifo.h>

#include <linux/kref.h>

#include <linux/mutex.h>

#include <linux/tty_buffer.h>
@@ -67,6 +68,7 @@ extern const struct tty_port_client_operations tty_port_default_client_ops; 
 * @mutex: locking, for open, shutdown and other port operations

 * @buf_mutex: @xmit_buf alloc lock

 * @xmit_buf: optional xmit buffer used by some drivers

 * @xmit_fifo: optional xmit buffer used by some drivers

 * @close_delay: delay in jiffies to wait when closing the port

 * @closing_wait: delay in jiffies for output to be sent before closing

 * @drain_delay: set to zero if no pure time based drain is needed else set to
@@ -110,6 +112,7 @@ struct tty_port { 
	struct mutex		mutex;

	struct mutex		buf_mutex;

	unsigned char		*xmit_buf;

	DECLARE_KFIFO_PTR(xmit_fifo, unsigned char);

	unsigned int		close_delay;

	unsigned int		closing_wait;

	int			drain_delay;